Since code blocks do not support line wrap, a line of "code" that is longer than the available frame width gets a horizontal scroll bar. Sliding that scroll bar on the code block results in the thread's vertical scroll bar also moving, slinging the view upward by dozens of posts (regardless of which direction the code block's scroll bar is moved). This unexpected behavior is in addition to the expected behavior of the text of the code block being scrolled appropriately by its scroll bar. Post where effect was noticed: https://robertsspaceindustries.com/spectrum/community/SC/forum/3/thread/star-citizen-economy-and-employment/1251513 Browser specs: Firefox Quantum 60.0.2 (64-bit)